I need help in adding external JAR files in java

I have problem in adding external JAR files into my Java project.

The external JAR files are provided by hardware device so we can connect to that device using the JAR files.

The error I get when I use some of the classes in the JAR file is:
exception in thread "main" java.lang.unsatisfiedlinkerror: no ibscanultimate in java.library.path